/* ----------------------------------------------------------------------
 * Project:      CMSIS DSP Library
 * Title:        arm_biquad_cascade_df1_q15.c
 * Description:  Processing function for the Q15 Biquad cascade DirectFormI(DF1) filter
 *
 * $Date:        18. March 2019
 * $Revision:    V1.6.0
 *
 * Target Processor: Cortex-M cores
 * -------------------------------------------------------------------- */
/*
 * Copyright (C) 2010-2019 ARM Limited or its affiliates. All rights reserved.
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * Licensed under the Apache License, Version 2.0 (the License); you may
 * not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an AS IS BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "arm_math.h"

/**
  @ingroup groupFilters
 */

/**
  @addtogroup BiquadCascadeDF1
  @{
 */

/**
  @brief         Processing function for the Q15 Biquad cascade filter.
  @param[in]     S         points to an instance of the Q15 Biquad cascade structure
  @param[in]     pSrc      points to the block of input data
  @param[out]    pDst      points to the location where the output result is written
  @param[in]     blockSize number of samples to process
  @return        none

  @par           Scaling and Overflow Behavior
                   The function is implemented using a 64-bit internal accumulator.
                   Both coefficients and state variables are represented in 1.15 format and multiplications yield a 2.30 result.
                   The 2.30 intermediate results are accumulated in a 64-bit accumulator in 34.30 format.
                   There is no risk of internal overflow with this approach and the full precision of intermediate multiplications is preserved.
                   The accumulator is then shifted by <code>postShift</code> bits to truncate the result to 1.15 format by discarding the low 16 bits.
                   Finally, the result is saturated to 1.15 format.
  @remark
                   Refer to \ref arm_biquad_cascade_df1_fast_q15() for a faster but less precise implementation of this filter.
 */

#if defined(ARM_MATH_MVEI)

void arm_biquad_cascade_df1_q15(
	const arm_biquad_casd_df1_inst_q15 *S,
	const q15_t *pSrc,
	q15_t *pDst,
	uint32_t blockSize)
{
	const q15_t    *pIn = pSrc; /*  input pointer initialization  */
	q15_t          *pOut = pDst;        /*  output pointer initialization */
	int             shift;
	uint32_t        sample, stages = S->numStages;      /*  loop counters                 */
	int             postShift = S->postShift;
	q15x8_t         bCoeffs0, bCoeffs1, bCoeffs2, bCoeffs3;     /*  Coefficients vector           */
	q15_t          *pState = S->pState; /*  pState pointer initialization */
	q15x8_t         inVec0;
	int64_t         acc;
	const q15_t     *pCoeffs = S->pCoeffs;       /*  coeff pointer initialization  */
	q31_t           out, out1;

	shift = (15 - postShift) - 32;

	do {
		q15_t           a2 = pCoeffs[5];
		q15_t           a1 = pCoeffs[4];

		bCoeffs0 = vdupq_n_s16(0);
		bCoeffs0[0] = pCoeffs[3];       // b2
		bCoeffs0[1] = pCoeffs[2];       // b1
		bCoeffs0[2] = pCoeffs[0];       // b0

		uint32_t        zero = 0;
		bCoeffs1 = bCoeffs0;
		bCoeffs1 = vshlcq_s16(bCoeffs1, &zero, 16);

		bCoeffs2 = bCoeffs1;
		bCoeffs2 = vshlcq_s16(bCoeffs2, &zero, 16);

		bCoeffs3 = bCoeffs2;
		bCoeffs3 = vshlcq_s16(bCoeffs3, &zero, 16);

		bCoeffs0[6] = a2;
		bCoeffs0[7] = a1;
		bCoeffs1[7] = a2;
		bCoeffs1[6] = a1;

		bCoeffs2 =
			vsetq_lane_s32(vgetq_lane_s32((q31x4_t) bCoeffs0, 3), (q31x4_t) bCoeffs2, 3);
		bCoeffs3 =
			vsetq_lane_s32(vgetq_lane_s32((q31x4_t) bCoeffs1, 3), (q31x4_t) bCoeffs3, 3);


		/* 2 first elements are garbage, will be updated with history */
		inVec0 = vld1q(pIn - 2);
		pIn += 2;

		inVec0[0] = pState[1];
		inVec0[1] = pState[0];
		inVec0[6] = pState[3];
		inVec0[7] = pState[2];

		acc = vmlaldavq(bCoeffs0, inVec0);
		acc = sqrshrl_sat48(acc, shift);
		out1 = (q31_t)((acc >> 32) & 0xffffffff);

		inVec0[6] = out1;
		acc = vmlaldavq(bCoeffs1, inVec0);
		acc = sqrshrl_sat48(acc, shift);
		out = (q31_t)((acc >> 32) & 0xffffffff);

		inVec0[7] = out;
		*pOut++ = (q15_t) out1;
		*pOut++ = (q15_t) out;

		acc = vmlaldavq(bCoeffs2, inVec0);
		acc = sqrshrl_sat48(acc, shift);
		out1 = (q31_t)((acc >> 32) & 0xffffffff);


		inVec0[6] = out1;
		acc = vmlaldavq(bCoeffs3, inVec0);
		acc = sqrshrl_sat48(acc, shift);
		out = (q31_t)((acc >> 32) & 0xffffffff);

		/*
		 * main loop
		 */
		sample = (blockSize - 4) >> 2U;
		/* preload (efficient scheduling) */
		inVec0 = vld1q(pIn);
		pIn += 4;

		/*
		 * Compute 4 outputs at a time.
		 */
		while (sample > 0U) {

			inVec0[6] = out1;
			inVec0[7] = out;

			/* store */
			*pOut++ = (q15_t) out1;
			*pOut++ = (q15_t) out;

			/*
			 * in       { x0  x1  x2  x3  x4  x5  yn2  yn1 }
			 *                          x
			 * bCoeffs0 { b2  b1  b0   0   0   0   a2  a1 }
			 *
			 */
			acc = vmlaldavq(bCoeffs0, inVec0);
			/* shift + saturate to 16 bit */
			acc = sqrshrl_sat48(acc, shift);
			out1 = (q31_t)((acc >> 32) & 0xffffffff);
			inVec0[6] = out1;

			/*
			 * in       { x0  x1  x2  x3  x4  x5  y0  yn1 }
			 *                          x
			 * bCoeffs1 {  0  b2  b1  b0   0   0  a1  a2 }
			 */
			acc = vmlaldavq(bCoeffs1, inVec0);
			acc = sqrshrl_sat48(acc, shift);
			out = (q31_t)((acc >> 32) & 0xffffffff);

			*pOut++ = (q15_t) out1;
			*pOut++ = (q15_t) out;


			inVec0[7] = out;
			/*
			 * in       { x0  x1  x2  x3  x4  x5  y0  yp1 }
			 *                         x
			 * bCoeffs2 { 0   0   b2  b1  b0   0  a2  a1 }
			 */
			acc = vmlaldavq(bCoeffs2, inVec0);
			acc = sqrshrl_sat48(acc, shift);
			out1 = (q31_t)((acc >> 32) & 0xffffffff);
			inVec0[6] = out1;

			/*
			 * in       { x0  x1  x2  x3  x4  x5  y0  yp1 }
			 *                         x
			 * bCoeffs2 {  0   0   0  b2  b1  b0  a1  a2  }
			 */
			acc = vmlaldavq(bCoeffs3, inVec0);
			acc = sqrshrl_sat48(acc, shift);
			out = (q31_t)((acc >> 32) & 0xffffffff);

			inVec0 = vld1q(pIn);
			pIn += 4;

			/* decrement the loop counter  */
			sample--;
		}

		*pOut++ = (q15_t) out1;
		*pOut++ = (q15_t) out;

		/*
		 * Tail handling
		 */
		int32_t         loopRemainder = blockSize & 3;

		if (loopRemainder == 3) {
			inVec0[6] = out1;
			inVec0[7] = out;

			acc = vmlaldavq(bCoeffs0, inVec0);
			acc = sqrshrl_sat48(acc, shift);
			out1 = (q31_t)((acc >> 32) & 0xffffffff);
			inVec0[6] = out1;

			acc = vmlaldavq(bCoeffs1, inVec0);
			acc = sqrshrl_sat48(acc, shift);
			out = (q31_t)((acc >> 32) & 0xffffffff);

			*pOut++ = (q15_t) out1;
			*pOut++ = (q15_t) out;

			inVec0[7] = out;
			acc = vmlaldavq(bCoeffs2, inVec0);
			acc = sqrshrl_sat48(acc, shift);
			out1 = (q31_t)((acc >> 32) & 0xffffffff);
			*pOut++ = (q15_t) out1;

			/* Store the updated state variables back into the pState array */
			pState[0] = vgetq_lane_s16(inVec0, 4);
			pState[1] = vgetq_lane_s16(inVec0, 3);
			pState[3] = out;
			pState[2] = out1;

		} else if (loopRemainder == 2) {
			inVec0[6] = out1;
			inVec0[7] = out;

			acc = vmlaldavq(bCoeffs0, inVec0);
			acc = sqrshrl_sat48(acc, shift);
			out1 = (q31_t)((acc >> 32) & 0xffffffff);
			inVec0[6] = out1;

			acc = vmlaldavq(bCoeffs1, inVec0);
			acc = sqrshrl_sat48(acc, shift);
			out = (q31_t)((acc >> 32) & 0xffffffff);

			*pOut++ = (q15_t) out1;
			*pOut++ = (q15_t) out;

			/* Store the updated state variables back into the pState array */
			pState[0] = vgetq_lane_s16(inVec0, 3);
			pState[1] = vgetq_lane_s16(inVec0, 2);
			pState[3] = out1;
			pState[2] = out;
		} else if (loopRemainder == 1) {

			inVec0[6] = out1;
			inVec0[7] = out;

			acc = vmlaldavq(bCoeffs0, inVec0);
			acc = sqrshrl_sat48(acc, shift);
			out1 = (q31_t)((acc >> 32) & 0xffffffff);
			*pOut++ = (q15_t) out1;

			/* Store the updated state variables back into the pState array */
			pState[0] = vgetq_lane_s16(inVec0, 2);
			pState[1] = vgetq_lane_s16(inVec0, 1);
			pState[3] = out;
			pState[2] = out1;


		} else {
			/* Store the updated state variables back into the pState array */
			pState[0] = vgetq_lane_s16(inVec0, 1);
			pState[1] = vgetq_lane_s16(inVec0, 0);
			pState[3] = out1;
			pState[2] = out;
		}

		pState += 4;
		pCoeffs += 6;

		/*
		 * The first stage goes from the input buffer to the output buffer.
		 * Subsequent stages occur in-place in the output buffer
		 */
		pIn = pDst;
		/*
		 * Reset to destination pointer
		 */
		pOut = pDst;
	} while (--stages);
}
#else
void arm_biquad_cascade_df1_q15(
	const arm_biquad_casd_df1_inst_q15 *S,
	const q15_t *pSrc,
	q15_t *pDst,
	uint32_t blockSize)
{


#if defined (ARM_MATH_DSP)

	const q15_t *pIn = pSrc;                             /* Source pointer */
	q15_t *pOut = pDst;                            /* Destination pointer */
	q31_t in;                                      /* Temporary variable to hold input value */
	q31_t out;                                     /* Temporary variable to hold output value */
	q31_t b0;                                      /* Temporary variable to hold bo value */
	q31_t b1, a1;                                  /* Filter coefficients */
	q31_t state_in, state_out;                     /* Filter state variables */
	q31_t acc_l, acc_h;
	q63_t acc;                                     /* Accumulator */
	q15_t *pState = S->pState;                     /* State pointer */
	const q15_t *pCoeffs = S->pCoeffs;                   /* Coefficient pointer */
	int32_t lShift = (15 - (int32_t) S->postShift);       /* Post shift */
	uint32_t sample, stage = (uint32_t) S->numStages;     /* Stage loop counter */
	int32_t uShift = (32 - lShift);

	do {
		/* Read the b0 and 0 coefficients using SIMD  */
		b0 = read_q15x2_ia((q15_t **) &pCoeffs);

		/* Read the b1 and b2 coefficients using SIMD */
		b1 = read_q15x2_ia((q15_t **) &pCoeffs);

		/* Read the a1 and a2 coefficients using SIMD */
		a1 = read_q15x2_ia((q15_t **) &pCoeffs);

		/* Read the input state values from the state buffer:  x[n-1], x[n-2] */
		state_in = read_q15x2_ia(&pState);

		/* Read the output state values from the state buffer:  y[n-1], y[n-2] */
		state_out = read_q15x2_da(&pState);

		/* Apply loop unrolling and compute 2 output values simultaneously. */
		/*      The variable acc hold output values that are being computed:
		 *
		 *    acc =  b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2]
		 *    acc =  b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2]
		 */
		sample = blockSize >> 1U;

		/* First part of the processing with loop unrolling.  Compute 2 outputs at a time.
		 ** a second loop below computes the remaining 1 sample. */
		while (sample > 0U) {

			/* Read the input */
			in = read_q15x2_ia((q15_t **) &pIn);

			/* out =  b0 * x[n] + 0 * 0 */
			out = __SMUAD(b0, in);

			/* acc +=  b1 * x[n-1] +  b2 * x[n-2] + out */
			acc = __SMLALD(b1, state_in, out);
			/* acc +=  a1 * y[n-1] +  a2 * y[n-2] */
			acc = __SMLALD(a1, state_out, acc);

			/* The result is converted from 3.29 to 1.31 if postShift = 1, and then saturation is applied */
			/* Calc lower part of acc */
			acc_l = acc & 0xffffffff;

			/* Calc upper part of acc */
			acc_h = (acc >> 32) & 0xffffffff;

			/* Apply shift for lower part of acc and upper part of acc */
			out = (uint32_t) acc_l >> lShift | acc_h << uShift;

			out = __SSAT(out, 16);

			/* Every time after the output is computed state should be updated. */
			/* The states should be updated as:  */
			/* Xn2 = Xn1 */
			/* Xn1 = Xn  */
			/* Yn2 = Yn1 */
			/* Yn1 = acc */
			/* x[n-N], x[n-N-1] are packed together to make state_in of type q31 */
			/* y[n-N], y[n-N-1] are packed together to make state_out of type q31 */

#ifndef  ARM_MATH_BIG_ENDIAN
			state_in  = __PKHBT(in, state_in, 16);
			state_out = __PKHBT(out, state_out, 16);
#else
			state_in  = __PKHBT(state_in >> 16, (in >> 16), 16);
			state_out = __PKHBT(state_out >> 16, (out), 16);
#endif /* #ifndef  ARM_MATH_BIG_ENDIAN */

			/* out =  b0 * x[n] + 0 * 0 */
			out = __SMUADX(b0, in);
			/* acc +=  b1 * x[n-1] +  b2 * x[n-2] + out */
			acc = __SMLALD(b1, state_in, out);
			/* acc +=  a1 * y[n-1] + a2 * y[n-2] */
			acc = __SMLALD(a1, state_out, acc);

			/* The result is converted from 3.29 to 1.31 if postShift = 1, and then saturation is applied */
			/* Calc lower part of acc */
			acc_l = acc & 0xffffffff;

			/* Calc upper part of acc */
			acc_h = (acc >> 32) & 0xffffffff;

			/* Apply shift for lower part of acc and upper part of acc */
			out = (uint32_t) acc_l >> lShift | acc_h << uShift;

			out = __SSAT(out, 16);

			/* Store the output in the destination buffer. */
#ifndef  ARM_MATH_BIG_ENDIAN
			write_q15x2_ia(&pOut, __PKHBT(state_out, out, 16));
#else
			write_q15x2_ia(&pOut, __PKHBT(out, state_out >> 16, 16));
#endif /* #ifndef  ARM_MATH_BIG_ENDIAN */

			/* Every time after the output is computed state should be updated. */
			/* The states should be updated as:  */
			/* Xn2 = Xn1 */
			/* Xn1 = Xn  */
			/* Yn2 = Yn1 */
			/* Yn1 = acc */
			/* x[n-N], x[n-N-1] are packed together to make state_in of type q31 */
			/* y[n-N], y[n-N-1] are packed together to make state_out of type q31 */
#ifndef  ARM_MATH_BIG_ENDIAN
			state_in  = __PKHBT(in >> 16, state_in, 16);
			state_out = __PKHBT(out, state_out, 16);
#else
			state_in  = __PKHBT(state_in >> 16, in, 16);
			state_out = __PKHBT(state_out >> 16, out, 16);
#endif /* #ifndef  ARM_MATH_BIG_ENDIAN */

			/* Decrement loop counter */
			sample--;
		}

		/* If the blockSize is not a multiple of 2, compute any remaining output samples here.
		 ** No loop unrolling is used. */

		if ((blockSize & 0x1U) != 0U) {
			/* Read the input */
			in = *pIn++;

			/* out =  b0 * x[n] + 0 * 0 */
#ifndef  ARM_MATH_BIG_ENDIAN
			out = __SMUAD(b0, in);
#else
			out = __SMUADX(b0, in);
#endif /* #ifndef  ARM_MATH_BIG_ENDIAN */

			/* acc =  b1 * x[n-1] + b2 * x[n-2] + out */
			acc = __SMLALD(b1, state_in, out);
			/* acc +=  a1 * y[n-1] + a2 * y[n-2] */
			acc = __SMLALD(a1, state_out, acc);

			/* The result is converted from 3.29 to 1.31 if postShift = 1, and then saturation is applied */
			/* Calc lower part of acc */
			acc_l = acc & 0xffffffff;

			/* Calc upper part of acc */
			acc_h = (acc >> 32) & 0xffffffff;

			/* Apply shift for lower part of acc and upper part of acc */
			out = (uint32_t) acc_l >> lShift | acc_h << uShift;

			out = __SSAT(out, 16);

			/* Store the output in the destination buffer. */
			*pOut++ = (q15_t) out;

			/* Every time after the output is computed state should be updated. */
			/* The states should be updated as:  */
			/* Xn2 = Xn1 */
			/* Xn1 = Xn  */
			/* Yn2 = Yn1 */
			/* Yn1 = acc */
			/* x[n-N], x[n-N-1] are packed together to make state_in of type q31 */
			/* y[n-N], y[n-N-1] are packed together to make state_out of type q31 */
#ifndef  ARM_MATH_BIG_ENDIAN
			state_in = __PKHBT(in, state_in, 16);
			state_out = __PKHBT(out, state_out, 16);
#else
			state_in = __PKHBT(state_in >> 16, in, 16);
			state_out = __PKHBT(state_out >> 16, out, 16);
#endif /* #ifndef  ARM_MATH_BIG_ENDIAN */
		}

		/* The first stage goes from the input wire to the output wire.  */
		/* Subsequent numStages occur in-place in the output wire  */
		pIn = pDst;

		/* Reset the output pointer */
		pOut = pDst;

		/* Store the updated state variables back into the state array */
		write_q15x2_ia(&pState, state_in);
		write_q15x2_ia(&pState, state_out);

		/* Decrement loop counter */
		stage--;

	} while (stage > 0U);

#else

	const q15_t *pIn = pSrc;                             /* Source pointer */
	q15_t *pOut = pDst;                            /* Destination pointer */
	q15_t b0, b1, b2, a1, a2;                      /* Filter coefficients */
	q15_t Xn1, Xn2, Yn1, Yn2;                      /* Filter state variables */
	q15_t Xn;                                      /* temporary input */
	q63_t acc;                                     /* Accumulator */
	int32_t shift = (15 - (int32_t) S->postShift); /* Post shift */
	q15_t *pState = S->pState;                     /* State pointer */
	const q15_t *pCoeffs = S->pCoeffs;                   /* Coefficient pointer */
	uint32_t sample, stage = (uint32_t) S->numStages;     /* Stage loop counter */

	do {
		/* Reading the coefficients */
		b0 = *pCoeffs++;
		pCoeffs++;  // skip the 0 coefficient
		b1 = *pCoeffs++;
		b2 = *pCoeffs++;
		a1 = *pCoeffs++;
		a2 = *pCoeffs++;

		/* Reading the state values */
		Xn1 = pState[0];
		Xn2 = pState[1];
		Yn1 = pState[2];
		Yn2 = pState[3];

		/* The variables acc holds the output value that is computed:
		 *    acc =  b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2]
		 */

		sample = blockSize;

		while (sample > 0U) {
			/* Read the input */
			Xn = *pIn++;

			/* acc =  b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] */
			/* acc =  b0 * x[n] */
			acc = (q31_t) b0 * Xn;

			/* acc +=  b1 * x[n-1] */
			acc += (q31_t) b1 * Xn1;
			/* acc +=  b[2] * x[n-2] */
			acc += (q31_t) b2 * Xn2;
			/* acc +=  a1 * y[n-1] */
			acc += (q31_t) a1 * Yn1;
			/* acc +=  a2 * y[n-2] */
			acc += (q31_t) a2 * Yn2;

			/* The result is converted to 1.31  */
			acc = __SSAT((acc >> shift), 16);

			/* Every time after the output is computed state should be updated. */
			/* The states should be updated as:  */
			/* Xn2 = Xn1 */
			/* Xn1 = Xn  */
			/* Yn2 = Yn1 */
			/* Yn1 = acc */
			Xn2 = Xn1;
			Xn1 = Xn;
			Yn2 = Yn1;
			Yn1 = (q15_t) acc;

			/* Store the output in the destination buffer. */
			*pOut++ = (q15_t) acc;

			/* decrement the loop counter */
			sample--;
		}

		/*  The first stage goes from the input buffer to the output buffer. */
		/*  Subsequent stages occur in-place in the output buffer */
		pIn = pDst;

		/* Reset to destination pointer */
		pOut = pDst;

		/*  Store the updated state variables back into the pState array */
		*pState++ = Xn1;
		*pState++ = Xn2;
		*pState++ = Yn1;
		*pState++ = Yn2;

	} while (--stage);

#endif /* #if defined (ARM_MATH_DSP) */

}
#endif /* defined(ARM_MATH_MVEI) */

/**
  @} end of BiquadCascadeDF1 group
 */
